What does a bell pit look like? shallow coal workings

As you can see in the picture this is what a bell pit would look like. Bell pits were excavated way back in the 15th hundreds and continued to be excavated up to early 19 hundreds. Back then anyone could dig for coal many people dug coal out of the ground just to heat their homes, or shacks and some for-profit just to make a living. The tools back then were very basic, picks, shovels and steel spikes many of the bell pits were dug in the soft ground some went up to 6m deep dependent on the thickness of the coal seam but many were only 3-4m deep. once the bell pit became unstable then it was abandoned some filled in with the excavations from the next bell pit and some just left for nature to sort out this was mostly dependent of the location.